Igniter plug



- E. W. PIERCE Jan. 16, 1962 IGNITER PLUG 2 Sheets-Sheet 1 Filed Nov.19, 1956 INVENTOR. faz/d fierae AT'IURNEK E. W. PIERCE IGNITER PLUG Jan.16, 1962 2 Sheets-Sheet 2 Filed Nov. 19, 1956 INVENTOIR. far/flfiwce A7' TOANE Y United States Patent 3,017,530 IGNITER PLUG Earl W. Pierce,Flint, Nl'ich., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaare Filed Nov. 19, 1956, Ser. No. 623,090 3 Claims.(Cl. 313-115) The present invention relates to ignition devices for fuelburners and more particularly to igniter plugs of the straight orangular type having means for supplying cooling air to the interiorthereof, such plugs being generally employed in the ignition of fuelsupplied to the combustion chambers of gas turbines. A device of theangular type is illustrated and described in the inventors copendingapplication Serial No. 406,171, filed January 26, 1954, and a device ofthe straight type i illustrated and described in Patent 2,609,808 to W.A. Bychinsky, issued September 9, 1952.

It has become the practice in the art to provide the steel body of theigniter plug with only a single port for the admission of cooling air tothe plug in order to increase the life of the plug by reducing thetemperature of the insulator and the electrodes and by minimizing thebuildup of carbon deposits on the insulator and on the electrodes.However, this expedient in angle-type plugs has given rise to theproblem of interchangeability and the necessity for having availableright-hand and lefthand igniter plugs. This problem results from thefact that jet engines are generally provided with at least two igniterplugs, commonly of the angle type, positioned on the surface of theengine shell with their angular portions directed toward each other inorder to enable the use of the shortest possible length of ignitioncable from the power box to the plugs. It is thus apparent that thesingle air inlet port would have to be on opposite sides of the shells.Similarly, since but a single air cooling port was used, it wasessential to provide means for mounting both the straight and angulartype plug in the engine in but a single position so as to locate theplugs with the air cooling port directed in the upstream direction ofthe air passing through the engine. Thus, not only is it necessary inusing the prior art type of construction to fabricate two differentmodels of the same angle-type plug but the necessity for providing allplugs with polarized mounting means to assure proper positioning undulycomplicates the assembly procedure of the plug in the engine. A typicalconstruction for assuring proper positioning is that utilizing thepolarized mounting flange disclosed and described in the aforesaidpatent.

Accordingly, it is an object of the present invention to provide anigniter plug adapted to be positioned in a combustion chamber and soconstructed as to provide a cooling stream of air within the plug shellregardless of the installation position on the engine. It is anotherobject of my invention to provide an elbow-type igniter plug soconstructed and arranged that air cooling ports are directed upstream tothe direction of air flow regardless of the mounting position of theplug on the engine.

These and other objects of my invention are attained by providing anigniter plug having means provided on substantially opposite sides ofthe shell adapted to direct the flow of air about the insulator andinner surface of the shell and out through the firing end.

A better understanding of my invention may be had by reference to thedescription which follows and the accompanying drawings in which:

FIGURE 1 is a sectional view through an igniter plug constructed inaccordance with my invention;'

FIGURE 2 is a sectional view taken on line 22;

FIGURE 3 is a perspective view of the air deflecting bafile of myinvention;

FIGURE 4 is a view with portions broken away and in section showing afurther embodiment of my invention;

FIGURE 5 is a view of the igniter plug taken along line 55;

FIGURE 6 is a perspective view of the air deflecting bafile utilized inthe embodiment shown in FIGURE 4.

Referring now to FIGURE 1, there is Shown an elbowtype igniter plug ofthe type more fully described in my aforesaid copending application. Thedevice shown in FIGURE 1 is the preferred embodiment of my invention andcomprises a body 1 having a shell portion 3, an angularly connectingshield sleeve portion 5 and a mounting pad 7. As is more clearly shownin FIGURE 5 with respect to the second embodiment of my invention, themounting pad 7 is provided with a pair of bolt holes 9 the central axesof which lie in the same plane as that of the central axis of theigniter plug thus forming a nonpolarized mounting construction to enablethe plug to be mounted in more than a single position in the combustionchamber. As is more fully disclosed in my aforementioned copendingapplication, a center electrode subassembly 11 is positioned within andin spaced relationship to the body 1 and comprises an insulator member13 having a center electrode 15 positioned concentrically therein, theouter end 17 of the insulator being adapted to receive an electricalcable (not shown) for electrical connection with the upper end of thecenter electrode.

As has been discussed with reference to the prior art, it has been foundnecessary to provide the shell 3 with means for introducing cooling airinto the space between the insulator 1'3 and the shell. As is clearlyshown in FIGURES 1 and 2, the shell 3 is provided with air cooling ports19 and 21 on substantially opposite sides thereof thus making itpossible to mount the igniter plug in either of two positions with theangular shield sleeve portion 5 of the plug directed in either of twopositions apart. In this manner, it is no longer necessary to providethe igniter plug with a polarized mounting since either air coolingports 19 or '21 will be directed upstream of the flow of cooling airthrough the jet engine.

In order to insure the flow of sufiicient cooling air about theinsulator 13 and out through the firing end of the igniter plug, it hasbeen found advisable to provide an air deflecting baffle in the annularspace between the insulator and the shell 3 in a position opposite theair cooling ports. As is clearly shown in FIGURES 1 and 2, the airdeflecting baffie of my preferred embodiment comprises a tubular member23 having a plurality of spacer lugs 25 positioned in spaced apartrelationship on the outer lower surface thereof, tubular member 23 beingadapted for positioning within the shell in spaced apart relationship toboth the shell 3 and the insulator 13. As is clearly shown in FIGURES 1and 3, the tubular deflecting baffie 23 is formed with an upper portion27 of enlarged diameter which is adapted to be securely positioned uponthe enlarged portion 14 of the insulator 13 thus retaining thedeflecting baflle 23 in fixed position about the insulator. As isdisclosed in detail in my aforesaid patent application, the enlargedupper portion 27 is machined both on its outer cylindrical surface 29and on its lower end surface 31 to position the center electrodesubassembly 11 concentrically within the shell 3 with the centerelectrode 15 concentric to the lower end 4 of the shell whichconstitutes the ground electrode of the igniter plug. It should be notedat this point that the air deflecting bafile 23 may be positioned withinthe shell 3 in any suitable manner other than here described. Theprovision of the air deflecting baffle precludes the flow of substantialquantities of cooling air entering one set of ports out the oppositelydisposed set of ports without contacting the lower end of the insulatorwith the result that the cooling of the lower end of the igniter plug ismade ineffective.

It is thus apparent from the description set forth above that I haveprovided an igniter plug so constructed as to enable adequate cooling ofthe plug regardless of whether the plug is mounted in either of twopositions in which the elbow portion thereof is directed 180 apart, thuseliminating the need for right and left-hand models of the same plug.Similarly, the need for a polarized mounting is eliminated thussimplifying assembly procedures.

In FIGURES 4, 5 and 6 I have shown a further em bodiment of my inventionwherein an air deflecting baflle of a different type than that utilizedin my preferred embodiment is positioned in the annular space betweenthe shell 3 and the insulator 13. As is clearly shown in FIGURES 4, 5and 6 the air deflecting baffle comprises a sleeve-like portion 33having a pair of oppositely disposed radial flanges 35 extendingoutwardly from the surface thereof. The sleeve 33 is adapted forrelatively close fitting about the lower portion of the insulator 13with the outer ends of the radial flanges 35 in close fitting contactwith the inner Wall surface of the shell 3. The flanges 35 arepositioned substantially opposite the air cooling ports 37 and 39 which,as in the embodiment of FIGURE 1, are positioned in the shell 3 insubstantially opposie sides thereof.

As is clearly shown in FIGURES 5 and 6, the air deflecting baffle may beformed of a pair of sheet metal stampings which may be secured togetherby spot welds or any other suitable means to form the sleeve 33 andflanges 35. As shown, the ends of the flanges 35 may be bent over toform circumferentially extending portions 41 which fit against the innersurface of the shell 3. As shown in FIGURE 4, a shoulder 43 may beformed on the inner wall of the shell 3 to support the air deflectingbaffle in the annular space between the shell and the insulator 13. Aplurality of bypassing ports 45 may be provided in the lower end of theshell 3 in the event it is found that the operation of the plug is beinginterfered with due to an excess of cooling air being directed into thecombustion chamber through the firing end of the plug.

As in the case of the embodiment shown in FIGURE 1, the constructionshown in FIGURE 4 enables an igniter plug to be positioned within thecombustion chamber in more than a single position while still assuringthe availability of cooling air to the plug. Similarly, installation ofthe plug in the chamber is greatly simplified since there is no longer aneed for a polarized mounting means. It should also be recognized thatthe use of angle-type igniter plugs constructed in accordance with myinvention eliminates the necessity for having right-hand and lefthandmodels of the same plug.

While I have illustrated several embodiments of my 5 invention, itshould be understood that other forms of the invention may be adopted,such forms being within the intended scope of my invention as set forthin the claims which follow.

What is claimed is:

1. In an angle-type igniter plug, a body member comprising a shellportion having a sleeve portion extending at an angle from the upperpart thereof, a mounting flange provided on the outer surface of saidshell portion, at least two continuously open ports provided in saidshell portion at positions substantially opposite each other betweensaid flange and the lower end of said shell, a plane through saidoppositely disposed ports and the longivtudinal axis of said plug beingsubstantially at right angles to a plane through the longitudinal axisof said sleeve portion and the longitudinal axis of said plug, saidmounting flange being non-polarized to enable the igniter plug to bemounted in more than a single position while assuring the availabilityof cooling air thereto.

2. In an elbow type igniter plug, a body member having a shell portioncomprising a ground electrode and a. shield sleeve portion extending atan angle from the upper end thereof and integral therewith, a centerelectrode subassembly comprising an angle type ceramic insulator andcenter electrode positioned substantially concentrically within saidbody in generally spaced apart relationship therewith, a mounting flangeprovided on the outer surface of said shell portion, at least twocontinuously open ports provided in said shell portion and each portbeing on substantially opposite sides thereof between said flange andthe lower end of said shell, a plane through said oppositely disposedports and the longitudinal axis of said center electrode beingsubstantially at right angles to a plane through the longitudinal axisof said shield sleeve portion and said center electrode, said mountingflange being non-polarized to enable the plug to be mounted with saidshield sleeve portion extending in one of two opposite directions whileassuring the availability of cooling air thereto.

3. An igniter plug as set forth in claim 2, wherein an air deflectingbaffle is positioned within said body member between said shell portionand said subassembly to deflect cooling air downwardly and into directcontact with the lower portion of said subassembly.

References Cited in the file of this patent UNITED STATES PATENTS2,081,503 Nowosielski May 25, 1937 2,493,743 Benson Jan. 10, 19502,609,808 Bychinsky Sept. 9, 1952 2,741,716 Arthur et a1. Apr. 10, 19562,875,365 Pierce Feb. 24, 1959 FOREIGN PATENTS 112,752 Great BritainIan. 24, 1918 206,665 Great Britain Nov. 15, 1923

